The present invention relates to a relief valve for hydraulic fluid, to be used to control the pressure in a duct, and whichs opens a communication between this duct and a reservoir when the pressure inside the duct exceeds a predetermined amount.
Such relief valves are well known in hydraulics, and have been given numerous designs. However, in some cases, it may be desirable that the pressure limitation occurs as a function of the pressure in another part of the hydraulic circuit. In this case, it is known to use two simple relief valves, or a single valve of a very complex design, with the result either of less reliability, or high costs, or large space required.